Special titanium dioxide for spherical particle color master batch and preparation method of special titanium dioxide

Abstract

The invention relates to the technical field of titanium dioxide, and particularly discloses special titanium dioxide for a spherical particle color master batch and a preparation method of the special titanium dioxide aiming at the problems that the dispersity of existing silicon-coated titanium dioxide and the spherical color master batch is poor, and the binding force of a coating layer of the titanium dioxide and a matrix is insufficient. The raw materials comprise 82-88% of a composite titanium dioxide base material, 6-9% of a polyfunctional group modified organic silicon coating material, 2-4% of a spherical adaptive coupling agent, 0.8-1.2% of a dispersion accelerator, 0.1-0.3% of a hindered amine light stabilizer and the balance of a pH regulator and deionized water. The polyfunctional group modified organic silicon coating material is prepared from the following raw materials: amino modified polydimethylsiloxane, epoxy trimethoxy silane and a fluorine-containing organic silicon monomer in a mass ratio of (4-6): (1-3): 1. The titanium dioxide with a composite crystal form is adopted as a base material, and a multi-structure coating layer is constructed on the surface of the composite titanium dioxide base material through a specific composite material and a limited process mode, so that the problems that the binding force of an existing titanium dioxide coating layer is poor, and titanium dioxide and spherical color master batches are not uniformly dispersed can be solved.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide technology, and more specifically, to a titanium dioxide for spherical particle masterbatch and its preparation method. Background Technology

[0002] Titanium dioxide is an inorganic chemical pigment with titanium dioxide as its main component. It has high refractive index, strong hiding power, excellent gloss and stable physicochemical properties. It is also non-toxic and has unique light absorption and scattering properties. It is mainly used as a raw material for white coatings and as an additive for chemical fibers and rubber. Its photocatalytic activity and safety also make it applicable in the fields of cosmetics, food additives, pharmaceuticals and catalysts.

[0003] Currently, common titanium dioxide production processes are mainly divided into the sulfuric acid process and the chlorination process. To improve the physical and chemical properties of titanium dioxide in applications such as coatings, it is common to coat the surface of titanium dioxide particles with materials such as organosilicon. For example, patent CN115926317A provides a color masterbatch, a colored reinforced polypropylene material, its preparation method, and its application. The color masterbatch includes 100 parts of first polypropylene, 0.5-10 parts of inorganic colored powder, 1-5 parts of titanium dioxide, 0.5-10 parts of barrier agent, 0.1-1 parts of lubricant, and 0.1-0.5 parts of antioxidant. The surface of the titanium dioxide used is coated with polysiloxane.

[0004] However, existing silicon-coated titanium dioxide has the following problems: On the one hand, the coating layer of conventional organosilicon-coated titanium dioxide is mostly irregular, which has poor compatibility with the spherical matrix of spherical masterbatch. It is easy for titanium dioxide particles to agglomerate and be exposed during the color masterbatch forming process, resulting in uneven coloring of the color masterbatch. On the other hand, the bonding force between the coating layer and the titanium dioxide matrix is ​​insufficient. During the high-temperature mixing and granulation process of spherical color masterbatch, the coating layer is easy to fall off, lose its protective effect on titanium dioxide, and thus affect the weather resistance and mechanical properties of the color masterbatch. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of poor dispersibility of existing silicon-coated titanium dioxide with the spherical matrix of spherical masterbatch and insufficient bonding force between the coating layer of titanium dioxide and the matrix.

[0006] This invention is achieved through the following technical solution:

[0007] This invention provides a titanium dioxide for spherical particle masterbatch. By mass fraction, the raw materials include: 82-88% composite titanium dioxide base, 6-9% multifunctional modified organosilicon coating material, 2-4% spherical adaptable coupling agent, 0.8-1.2% dispersant accelerator, 0.1-0.3% hindered amine light stabilizer, and the balance being pH adjuster and deionized water. The multifunctional modified organosilicon coating material is prepared from amino-modified polydimethylsiloxane, epoxytrimethoxysilane, and fluorinated organosilicon monomers in a mass ratio of 4-6:1-3:1.

[0008] Preferably, the preparation method of the multifunctional modified organosilicon coating material includes the following steps: A1. Take amino-modified polydimethylsiloxane, heat it, and dry it; separately take epoxy-trimethoxysilane and fluorinated organosilicon monomer, and dehydrate them respectively. A2 First, take amino-modified polydimethylsiloxane, mix it with anhydrous ethanol, stir and heat it, and react it at 35-40℃ for 10-20 min; then add epoxytrimethoxysilane dropwise at 0.3-0.5 mL / min, and continue to stir and react for 20-40 min; then cool it down to 25-30℃, add fluorinated organosilicon monomer, and stir and react at a constant temperature for 45-60 min; A3. The material system after step A2 is subjected to vacuum degassing to obtain a multifunctional modified organosilicon coating material, which is then sealed and stored away from light.

[0009] Preferably, the composite titanium dioxide base material includes anatase titanium dioxide and rutile titanium dioxide in a mass ratio of 8-9:1.

[0010] Preferably, the raw materials for preparing the spherical adaptable coupling agent include γ-methacryloyloxypropyltrimethoxysilane and rare earth modified titanate coupling agent in a mass ratio of 1-2:1, wherein the rare earth modified titanate coupling agent is isopropyltris(dioctylpyrophosphate) titanate modified by lanthanides.

[0011] Preferably, the preparation method of the spherical adaptable coupling agent includes the following steps: B1. Isopropyl tris(dioctylpyrophosphoryloxy) titanate, lanthanide compounds, and anhydrous ethanol were prepared in a mass ratio of 10:1 to 1.5:5. The lanthanide compounds and anhydrous ethanol were mixed and heated at 45-50℃ for 20-40 min. Then, isopropyl tris(dioctylpyrophosphoryloxy) titanate was added dropwise at 0.1-0.3 mL / min. After the addition was completed, the temperature was raised to 60-65℃ and stirred for 1-3 h. The mixture was then distilled under reduced pressure to obtain the rare earth modified titanate coupling agent. B2 Take the rare earth modified titanate coupling agent obtained in step B1, cool it to below 30°C, add γ-methacryloyloxypropyltrimethoxysilane, and stir at a constant temperature under nitrogen protection until the mixture is homogeneous to obtain a spherical suitable coupling agent.

[0012] Preferably, the raw materials for preparing the dispersion accelerator include equal masses of hyperbranched polyester dispersant and thermosensitive poly(N-isopropylacrylamide).

[0013] Preferably, the method for preparing the dispersion accelerator includes the following steps: C1 Take hyperbranched polyester dispersant, heat it, and dry it; separately take thermosensitive poly(N-isopropylacrylamide), and purify and dry it in sequence. C2 Take the hyperbranched polyester dispersant treated in step C1, add it to anhydrous methanol, and stir; then add thermosensitive poly(N-isopropylacrylamide) and continue stirring until completely dissolved; C3 Add an antioxidant to the material system obtained in step C2, stir until homogeneous, and then distill under reduced pressure to obtain a dispersion promoter.

[0014] The present invention also provides a method for preparing the above-mentioned titanium dioxide for spherical particle masterbatch, comprising the following steps: S1 Base Material Pretreatment: Take the composite titanium dioxide base material, add it to deionized water, adjust the pH value, then perform low-temperature plasma treatment, and then perform ultrasonic dispersion treatment to obtain a pretreated titanium dioxide suspension. S2 Constructing the pre-coating layer: Take the pretreated titanium dioxide suspension, add a spherical suitable coupling agent, heat and stir, and obtain a titanium dioxide particle suspension through microwave-assisted reaction; S3 Deposition of the main coating layer: Multifunctional modified organosilicon coating material was added to deionized water, followed by the addition of a hindered amine light stabilizer. The mixture was stirred to obtain a coating solution. The coating solution was then added dropwise to a suspension of titanium dioxide particles at a rate of 0.5-1 mL / min, while maintaining a constant temperature of 60-70°C and stirring to deposit the main coating layer. Subsequently, the mixture was cured at 70-80°C and 80-90°C for 20-40 min and 50-70 min, respectively, to obtain a coated titanium dioxide suspension. S4 Surface Grafting Treatment: Take a coated titanium dioxide suspension, add a dispersion accelerator, mix, heat to 75-80℃, keep warm and stir to react, and obtain a preliminary titanium dioxide suspension; S5 Post-Processing: The initial titanium dioxide suspension was cooled to room temperature, then pressure filtered, washed, vacuum dried, and then subjected to air jet milling, graded and sieved. Finally, the surface was sprayed with a silane coupling agent dilution to obtain titanium dioxide for spherical particle masterbatch.

[0015] Preferably, in step S2, the temperature is raised to 50-60°C, and the mixture is stirred at a constant temperature of 300-400 r / min with microwave-assisted power of 200-250 W for 30-40 min; in step S4, the temperature is raised to 75-80°C, and the mixture is stirred at a constant temperature of 700-800 r / min for 40-60 min.

[0016] Preferably, in step S5, the particle size D50 of the granules after grading and screening is 0.22-0.28 μm, and the particle size distribution range is ≤0.08 μm.

[0017] The technical solution of the present invention has the following beneficial effects: (1) The present invention uses composite crystal titanium dioxide as the base material and uses plasma to activate it. Through the dual combination mechanism of interface anchoring of composite crystal titanium dioxide and plasma surface activation, the bonding force between the coating layer and titanium dioxide is improved, solving the common problem of easy peeling of the coating layer on the surface of titanium dioxide.

[0018] (2) The coating layer of the present invention adopts a multifunctional coating material containing fluorine and light stabilizer modified by rare earth, which integrates weather resistance, shear resistance and anti-yellowing functions, solves the defects of traditional silicon-coated titanium dioxide with single function orientation and insufficient comprehensive performance, and is suitable for high-end scenarios such as outdoor spherical masterbatch.

[0019] (3) Construct a gradient cross-linked double-layer coating structure to achieve a double-layer coating effect with a dense inner layer and an elastic outer layer, which not only ensures a firm bond with the matrix, but also buffers high-temperature shear stress, taking into account both stability and compatibility.

[0020] (4) After forming a multi-structured coating layer on the surface of the composite titanium dioxide base material, the thermosensitive properties of poly(N-isopropylacrylamide) in the dispersion accelerator are used to achieve automatic protection during high-temperature mixing, which can significantly reduce the peeling rate of the coating layer and improve the tensile strength, impact toughness and mechanical properties of the masterbatch after molding. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer; where the manufacturers of the instruments, equipment, reagents, or raw materials used are not specified, they are all conventional products that can be purchased commercially.

[0022] This invention provides a titanium dioxide specifically for spherical particle masterbatch, comprising the following raw material components: ① Composite titanium dioxide base material: It is a composite material of anatase titanium dioxide (also known as type A titanium dioxide) and rutile titanium dioxide (also known as type R titanium dioxide) with a mass ratio of 8-9:1, accounting for 82-88% of the total raw material mass; ② Multifunctional modified organosilicon coating material: It is a compound of amino-modified polydimethylsiloxane, epoxy-trimethoxysilane, and fluorinated organosilicon monomer (such as trifluoropropyltrimethoxysilane) in a mass ratio of 4-6:1-3:1, accounting for 6-9% of the total raw material mass; among which, the number average molecular weight of amino-modified polydimethylsiloxane is controlled at 1000-3000 and the ammonia value is 0.8-1.2 mmol / g. When using this multifunctional modified organosilicon coating material, it is diluted to a mass concentration of 10-15%; ③ Spherical suitable coupling agent: It is a compound of γ-methacryloyloxypropyltrimethoxysilane and rare earth modified titanate coupling agent with a mass ratio of 1-2:1, accounting for 2-4% of the total raw material mass; wherein, the rare earth modified titanate coupling agent is isopropyltris(dioctylpyrophosphate) titanate modified by lanthanide elements (such as lanthanum and / or cerium). ④ Dispersion accelerator: It is a compound of equal mass of hyperbranched polyester dispersant and thermosensitive poly(N-isopropylacrylamide) (PNIPAM), accounting for 0.8-1.2% of the total raw material mass; wherein, the hyperbranched polyester dispersant contains terminal hydroxyl groups and the number average molecular weight is controlled at 5000-8000, and the number average molecular weight of the thermosensitive poly(N-isopropylacrylamide) is controlled at 8000-10000. ⑤ Hindered amine light stabilizers (HALS): accounting for 0.1-0.3% of the total raw material mass, they can be chemically bonded to the surface of the coating layer to further improve the weather resistance of the masterbatch; ⑥ The remainder consists of pH adjuster and deionized water. The pH adjuster is ammonia or dilute hydrochloric acid, etc.

[0023] In this invention, a composite titanium dioxide base material with two crystal forms is used. Type A titanium dioxide is used to ensure high hiding power, while type R titanium dioxide is used to improve weather resistance. This solves the problem that hiding power and weather resistance cannot be achieved simultaneously in single-crystal titanium dioxide. Furthermore, the crystal interface formed by the two can serve as an anchor point for the coating layer, which can further enhance the bonding force between the coating layer and the base material.

[0024] The preparation method of the multifunctional modified organosilicon coating material in this invention is as follows: (1) Take amino-modified polydimethylsiloxane, place it in a vacuum drying oven, and dry it for 1-3 hours at 80-90℃ and -0.10 to -0.08MPa vacuum to remove moisture in order to avoid compatibility due to hydrolysis; take epoxy trimethoxysilane and fluorinated organosilicon monomer separately and dehydrate them to control the water content ≤0.05wt% in order to avoid premature hydrolysis and condensation of siloxane.

[0025] (2) Take a three-necked flask and place it in a nitrogen protective atmosphere and a constant temperature water bath with stirring. Introduce the above-treated amino-modified polydimethylsiloxane and anhydrous ethanol respectively. Start stirring at 200-250 r / min and heat to 35-40℃. Keep stirring for 10-20 min. Then slowly add epoxytrimethoxysilane at 0.3-0.5 mL / min. During this period, keep purging with nitrogen to avoid air oxidation. After the addition is completed, continue stirring for 20-40 min. During this process, the amino and epoxy groups undergo slight pre-crosslinking to form a preliminary network structure, which can improve the density of the subsequent coating layer. After the reaction is completed, cool down to 25-30℃ and add fluorinated organosilicon monomer. Stir at 300-350 r / min for 45-60 min to make the fluorine groups uniformly dispersed in the organosilicon system.

[0026] (3) Place the material system after the above stirring is placed in a vacuum degassing tank and degas for 10-20 minutes under a vacuum of -0.10 to -0.05 MPa to remove bubbles in order to avoid pores during coating. The resulting multifunctional modified organosilicon coating material has a viscosity of 50-80 mPa·s (25℃) and a pH of 6.0-7.0. It should be sealed and protected from light and has an effective shelf life of 6 months. It can be diluted to 10-15 wt% before use.

[0027] A multi-component composite organosilicon coating material is used to coat the surface of a composite titanium dioxide base material through chemical bonding. The fluorine-containing groups can endow the coating layer with low surface energy, anti-fouling and UV aging resistance, while the strong electronegativity of fluorine atoms can enhance the cross-linking density of organosilicon molecular chains and improve the high-temperature shear resistance of the coating layer.

[0028] The preparation method of the spherical adaptable coupling agent in this invention is as follows: (1) Take isopropyltris(dioctylpyrophosphate) titanate, lanthanide compounds (lanthanum nitrate or cerium nitrate, purity ≥99.5%), and anhydrous ethanol in a mass ratio of 10:1-1.5:5. Take a three-necked flask, add anhydrous ethanol and lanthanide compounds, stir at 200-300 r / min, and heat to 45-50℃, continue stirring for 20-40 min to completely dissolve the lanthanide compounds and form a rare earth ion solution. Then, slowly add isopropyltris(dioctylpyrophosphate) titanate to the three-necked flask at 0.1-0.3 mL / min, keeping nitrogen protection during the process to avoid hydrolysis. After the addition is completed, heat to 60-65℃, keep warm and stir for 1-3 h to carry out the reaction. This process allows the pyrophosphate oxy group in the titanate molecule to react with rare earth ions (such as La). 3+ or Ce 3+ Coordination bonds are formed; after the reaction is completed, the above material system is placed under vacuum conditions of 60-80℃ and -0.10 to -0.08MPa to remove the solvent by vacuum distillation, and a viscous rare earth modified titanate coupling agent is obtained, wherein the rare earth element content is 5-8wt%.

[0029] (2) Take the rare earth modified titanate coupling agent prepared above and add it to a dry stirring tank. Cool it down to below 30°C and then add γ-methacryloyloxypropyltrimethoxysilane. Under nitrogen protection, stir at a constant temperature of 300-350 r / min for 30-40 min to make it fully mixed and uniform, i.e., without layering and precipitation, to obtain a spherical suitable coupling agent with a viscosity of 30-50 mPa·s (25°C) and a moisture content ≤0.1 wt%. Store it in a sealed container and avoid high temperature and humid environment.

[0030] A specific complex coupling agent is used, which includes a rare earth-modified titanate coupling agent. Rare earth elements can form coordination bonds, strengthening the multiple bonds between the coupling agent and the titanium dioxide matrix and the organosilicon coating layer. At the same time, the photostabilizing effect of rare earth ions can reduce the photocatalytic activity of titanium dioxide and prevent the masterbatch from yellowing during long-term use.

[0031] In this invention, the method for preparing the dispersion accelerator is as follows: (1) Take hyperbranched polyester dispersant and dry it for 2-5 hours at 90-110℃ and -0.10 to -0.09MPa vacuum to remove excess water and low molecular weight impurities; take thermosensitive polyN-isopropylacrylamide, recrystallize it with anhydrous methanol, purify it, and dry it at 50-70℃ for 1-3 hours to maintain its purity ≥99% and avoid impurities affecting its thermosensitivity.

[0032] (2) First, add anhydrous methanol to the mixing tank and cool it to 20-25°C. Then add the hyperbranched polyester dispersant treated above and stir at a constant temperature of 350-400 r / min for 10-30 min. Then add thermosensitive poly(N-isopropylacrylamide) powder and stir at a constant temperature of 450-500 r / min for 60-90 min until the powder is completely dissolved and there are no visible particles in the material system.

[0033] (3) Add 0.05wt% of antioxidant to the above-mentioned stirred material system to avoid the oxidative degradation of thermosensitive poly(N-isopropylacrylamide), and continue stirring for 10-20 min; then carry out vacuum distillation at 30-50℃ and -0.10 to -0.05MPa to remove anhydrous methanol and obtain a white powdered dispersion promoter with a moisture content of ≤0.5wt%.

[0034] In the dispersion accelerator system, the hyperbranched structure can provide more dispersion sites and improve the dispersion uniformity of titanium dioxide in the carrier resin; when PNIPAM is mixed at high temperature >32℃, it undergoes a conformational transformation to form a dense steric hindrance layer, which prevents the coating layer from falling off under high shear.

[0035] The preparation method of titanium dioxide for spherical particle masterbatch of the present invention includes the following steps: (1) Base material pretreatment Take the composite titanium dioxide base material and add it to deionized water to prepare a composite titanium dioxide suspension with a solid content of 30-40 wt%. Then, add a pH adjuster to adjust the pH value of the composite titanium dioxide suspension to 6.5-7.5. Then, place the composite titanium dioxide suspension in a low-temperature plasma treatment device with argon as the carrier gas, set the power to 150-200W, and treat for 5-8 minutes. Then, perform ultrasonic dispersion, during which nitrogen gas is introduced for protection. The ultrasonic power is 300-500W, the ultrasonic frequency is 25-40kHz, and the ultrasonic treatment is 15-20 minutes to complete the pretreatment of the base material, and obtain a pretreated titanium dioxide suspension for later use.

[0036] First, plasma etching is used to etch the surface of titanium dioxide to increase the number and activity of surface hydroxyl groups, providing more bonding sites for subsequent coupling agents and coating layers, thus solving the problem of insufficient activation in traditional pretreatment. Then, ultrasonic pretreatment is used to break up the initial agglomeration of anatase titanium dioxide matrix. At the same time, a neutral pH environment and nitrogen protection can prevent the surface hydroxyl groups of titanium dioxide from being destroyed, laying the foundation for the strong bonding of the subsequent coating layer.

[0037] (2) Constructing a pre-coating layer Take the pretreated titanium dioxide suspension, add a spherical suitable coupling agent, heat to 50-60℃, stir at a constant temperature of 300-400r / min, and then react with microwave assisted reaction at 200-250W power for 30-40min to obtain a titanium dioxide particle suspension with a pre-coated layer on the surface.

[0038] During the above reaction process, the coupling agent preferentially forms chemical bonds with the hydroxyl groups on the surface of the titanium dioxide matrix, constructing a pre-coating layer with spherical adaptive active sites on the surface of the titanium dioxide, which can improve the adhesion of the subsequent organosilicon coating layer and its compatibility with the spherical color masterbatch matrix.

[0039] (3) Deposition of the main coating layer A multifunctional modified organosilicon coating material is diluted with deionized water to a mass concentration of 10-15 wt%, and then a hindered amine light stabilizer is added and mixed to obtain a coating solution. Using a constant flow pump, the coating solution is added dropwise to a titanium dioxide particle suspension at a rate of 0.5-1 mL / min, while maintaining the material system temperature at 60-70℃ and stirring at 500-600 r / min to deposit the main coating layer on the surface of the titanium dioxide particles. Then, the material system is heated to 70-80℃ and held for 20-40 min, and then further heated to 80-90℃ and held for 50-70 min to achieve gradient cross-linking and curing of the main coating layer, forming a double-layer coating structure with a dense inner layer and an elastic outer layer, resulting in a coated titanium dioxide suspension with both surface adhesion and flexibility.

[0040] The amino and epoxy groups in the modified organosilicon coating material can undergo cross-linking reactions with the active sites of the pre-coating layer to form a dense and elastic organosilicon master coating layer on the surface of titanium dioxide. The spatial configuration of its molecular chain can be intercalated with the spherical structure of the spherical masterbatch, improving the compatibility between the two.

[0041] (4) Surface grafting treatment Take the coated titanium dioxide suspension, add the dispersion accelerator, mix, heat to 75-80℃, and stir at 700-800r / min for 40-60min to graft the dispersion accelerator onto the surface of the coated titanium dioxide particles to obtain the initial titanium dioxide suspension.

[0042] Through heating reaction, the dispersant can be grafted onto the surface of the organosilicon coating layer, reducing the surface tension of the coated titanium dioxide particles, improving their dispersibility in the spherical masterbatch carrier resin, and enhancing the shear resistance of the coating layer to prevent the coating layer from falling off during granulation.

[0043] (5) Post-processing The initial titanium dioxide suspension was cooled to room temperature, then filtered and washed. The filter cake was then placed in a vacuum drying oven and dried for 8-10 hours at 80-90℃ and a vacuum of -0.08 to -0.10 MPa. After drying, the material was placed in an air jet mill and subjected to multi-stage pulverization under a nitrogen atmosphere. The material was then sieved multiple times to separate particles with a particle size D50 of 0.22-0.28 μm and a particle size distribution range of ≤0.08 μm. This process improves the color uniformity during subsequent masterbatch production. The surface was then passivated by spraying with a 0.5% silane coupling agent dilution to obtain spherical titanium dioxide for masterbatch production.

[0044] In this invention, the particle size is precisely controlled to ensure that the particle size gradient of titanium dioxide particles and spherical masterbatch is matched, so as to avoid the problem of uneven dispersion caused by excessive particle size difference.

[0045] Example 1 Step 1: Prepare each component raw material separately.

[0046] ① Take type A titanium dioxide and type R titanium dioxide at a mass ratio of 8.5:1, crush and sieve them, mix them evenly, and prepare a composite titanium dioxide base material.

[0047] ② Take 5g of amino-modified polydimethylsiloxane, place it in a vacuum drying oven, and dry it for 2h at 85℃ and -0.09MPa vacuum to remove moisture; take another 2g of epoxytrimethoxysilane and 1g of trifluoropropyltrimethoxysilane, and dehydrate them respectively by passing them through a 4A molecular sieve column. Take a three-necked flask and place it in a nitrogen-protected atmosphere and a constant-temperature water bath with stirring. Pour in the amino-modified polydimethylsiloxane obtained above, add anhydrous ethanol until submerged, start stirring at 220 r / min, and heat to 40℃, stirring for 15 min. Then slowly add epoxytrimethoxysilane at 0.4 mL / min, purging with nitrogen during the process. After the addition is complete, continue stirring for 30 min. After the reaction is complete, cool down to below 30℃, add trifluoropropyltrimethoxysilane, and stir at 320 r / min for 55 min. Then place the material system after stirring in a vacuum degassing tank and degas for 15 min under a vacuum of -0.08 MPa to obtain a multifunctional modified organosilicon coating material.

[0048] ③ Take 10g of isopropyltris(dioctylpyrophosphoryloxy)titanate, 1.2g of lanthanum nitrate with a purity ≥99.5%, and 5g of anhydrous ethanol. Take a three-necked flask, add anhydrous ethanol and lanthanum nitrate, stir at 250r / min, and heat to 50℃, continuing to stir for 30min. Then, slowly add isopropyltris(dioctylpyrophosphoryloxy)titanate to the three-necked flask at 0.2mL / min, maintaining nitrogen protection during the process. After the addition is complete, heat to 65℃, keep warm and stir for 2h to carry out the reaction. After the reaction is complete, place the above material system under 70℃ and -0.09MPa vacuum conditions for vacuum distillation to remove the solvent, cool, and obtain a viscous rare earth modified titanate coupling agent. The rare earth modified titanate coupling agent and γ-methacryloxypropyltrimethoxysilane prepared above were added to a dry stirring tank at a mass ratio of 1:1.5. The mixture was stirred at a constant temperature of 320 r / min for 35 min under nitrogen protection to obtain a spherical suitable coupling agent.

[0049] ④ Take a hyperbranched polyester dispersant and dry it for 3 hours at 100℃ and -0.095MPa vacuum. Separately, take a thermosensitive poly(N-isopropylacrylamide), recrystallize it with anhydrous methanol, purify it, and dry it at 60℃ for 2 hours. First, add anhydrous methanol to a stirred tank, cool it to below 25℃, then add 0.5g of the above-treated hyperbranched polyester dispersant, and stir at a constant temperature of 380r / min for 20min. Then add 0.5g of thermosensitive poly(N-isopropylacrylamide) powder, and stir at a constant temperature of 480r / min for 70min until completely dissolved. Add about 0.05g of antioxidant 1010 to the above-dissolved material system, and continue stirring for 15min. Then, perform vacuum distillation at 40℃ and -0.08MPa vacuum to remove anhydrous methanol, obtaining a dispersion accelerator.

[0050] ⑤ Take an appropriate amount of light stabilizer HALS, an appropriate amount of ammonia water and dilute hydrochloric acid, and sufficient deionized water for later use.

[0051] Step 2: Take 85g of composite titanium dioxide base material and add it to deionized water to prepare a composite titanium dioxide suspension with a solid content of 35wt%. Adjust the pH value to 7.0 by adding ammonia and dilute hydrochloric acid. Then place it in a low-temperature plasma treatment device with argon as the carrier gas, set the power to 180W, and treat for 6 minutes. Then, under nitrogen protection, use 400W and 30kHz ultrasonic treatment for 18 minutes to obtain a pretreated titanium dioxide suspension.

[0052] Step 3: Take the pretreated titanium dioxide suspension, add 3g of spherical suitable coupling agent, heat to 55℃, stir at a constant temperature of 350r / min, and react with microwave assisted reaction at 220W power for 35min to obtain titanium dioxide particle suspension.

[0053] Step 4: Take 7.5g of multifunctional modified organosilicon coating material, dilute it with deionized water to a mass concentration of 12wt%, then add 0.2g of light stabilizer HALS, mix well to obtain a coating solution; use a constant flow pump to add the coating solution dropwise to the titanium dioxide particle suspension at a rate of 0.8mL / min, while maintaining the material system temperature at 65℃ and stirring at 550r / min to deposit a main coating layer on the surface of the titanium dioxide particles; then heat the material system to 75℃, hold for 30min, and then continue to heat to 85℃, hold for 60min to obtain a coated titanium dioxide suspension.

[0054] Step 5: Take the coated titanium dioxide suspension, add 1g of dispersion accelerator, mix, heat to 80℃, and stir at 780r / min for 50min to obtain the initial titanium dioxide suspension.

[0055] Step 6: Cool the initial titanium dioxide suspension to room temperature, filter and wash it, then place the filter cake in a vacuum drying oven and dry it for 9 hours at 85℃ and -0.09MPa vacuum. After drying, place the material in an air jet mill and perform multi-stage pulverization under a nitrogen atmosphere. Sieve it multiple times to separate particles with a particle size D50 of about 0.25μm and a particle size distribution span of about 0.06μm. Perform surface spray passivation treatment with a 0.5% mass concentration of silane coupling agent KH550 diluted solution to obtain titanium dioxide for spherical particle masterbatch.

[0056] Example 2 The difference between this embodiment and Embodiment 1 is that: ①The composite titanium dioxide base material is a mixture of type A titanium dioxide and type R titanium dioxide in a mass ratio of 8:1, with a total mass of 82g.

[0057] ②The mass ratio of amino-modified polydimethylsiloxane, epoxytrimethoxysilane, and trifluoropropyltrimethoxysilane in the multifunctional modified organosilicon coating material is 4:1:1, with a total mass of 6g; and during preparation, the drying temperature is 80℃, the drying time is 1h, and the degassing vacuum degree is -0.05MPa.

[0058] ③ The mass ratio of γ-methacryloyloxypropyltrimethoxysilane to rare earth modified titanate coupling agent in the spherical suitable coupling agent is 1:1, with a total mass of 2g; when preparing rare earth modified titanate, lanthanum nitrate is 1g, and the reaction time is 1h.

[0059] ④ The total mass of the dispersion accelerator is 0.8g, and the drying temperature of the hyperbranched polyester dispersant is 90℃ and the drying time is 2h.

[0060] ⑤ In steps 2-6, the plasma power is 150W and the treatment time is 5min; the ultrasonic power is 300W and the treatment time is 15min; the microwave power is 200W and the reaction time is 30min; the droplet acceleration rate of the main coating layer is 0.5mL / min; the gradient curing temperature is 70℃ for 20min and 80℃ for 50min; the particle size D50 after airflow pulverization is about 0.22μm and the distribution span is about 0.07μm.

[0061] Example 3 The difference between this embodiment and Embodiment 1 is that: ①The composite titanium dioxide base material is a mixture of type A titanium dioxide and type R titanium dioxide in a mass ratio of 9:1, with a total mass of 88g.

[0062] ②The mass ratio of amino-modified polydimethylsiloxane, epoxytrimethoxysilane, and trifluoropropyltrimethoxysilane in the multifunctional modified organosilicon coating material is 6:3:1, with a total mass of 9g; and during preparation, the drying temperature is 90℃, the drying time is 3h, and the degassing vacuum degree is -0.10MPa.

[0063] ③ The mass ratio of γ-methacryloyloxypropyltrimethoxysilane to rare earth modified titanate coupling agent in the spherical suitable coupling agent is 2:1, with a total mass of 4g; when preparing rare earth modified titanate, lanthanum nitrate is 1.5g, and the reaction time is 3h.

[0064] ④ The total mass of the dispersion accelerator is 1.2g, and the drying temperature of the hyperbranched polyester dispersant is 110℃ and the drying time is 5h.

[0065] ⑤ In steps 2-6, the plasma power is 200W and the treatment time is 8min; the ultrasonic power is 500W and the treatment time is 20min; the microwave power is 250W and the reaction time is 40min; the droplet acceleration rate of the main coating layer is 1.0mL / min; the gradient curing temperature is 80℃ for 40min and 90℃ for 70min; the particle size D50 after airflow pulverization is about 0.28μm and the distribution span is about 0.08μm.

[0066] Comparative Example 1 The difference between this comparative example and Example 1 is that the composite titanium dioxide base material is replaced with 85g of pure type A titanium dioxide, and there is no type R titanium dioxide. The other raw materials and processes are completely the same.

[0067] Comparative Example 2 The difference between this comparative example and Example 1 is that the rare earth modified titanate coupling agent in the spherical adaptor coupling agent is replaced with isopropyltris(dioctylpyrophosphate) titanate without rare earth element modification, while the other raw materials and processes are completely the same.

[0068] Comparative Example 3 The difference between this comparative example and Example 1 is that the low-temperature plasma treatment step is omitted in the base material pretreatment stage, while the other raw materials and processes are completely the same.

[0069] Comparative Example 4 The difference between this comparative example and Example 1 is that the multifunctional modified organosilicon coating material is replaced with 7.5g of single amino modified polydimethylsiloxane, no epoxy trimethoxysilane and fluorinated organosilicon monomer are added, and no hindered amine light stabilizer is added. The other raw materials and processes are completely the same.

[0070] Comparative Example 5 This comparative example uses the titanium dioxide preparation method of masterbatch mentioned in the background technology, that is, using 85g of type A titanium dioxide as base material and 7.5g of polysiloxane as coating material, it is ultrasonically dispersed at 400W for 18min, and then air-jet pulverized until the particle size D50 is about 0.3μm and the distribution span is about 0.15μm, to obtain titanium dioxide product.

[0071] Test case Samples: Examples 1-3, Comparative Examples 1-5 Take the above samples respectively, and then test their different material properties in sequence as follows, and summarize the test results in Table 1 below.

[0072] (1) Titanium dioxide dispersibility test The above samples were used as raw materials to prepare masterbatches according to existing technologies described in the background section. The masterbatches were then sliced, sputter-coated with gold, and the distribution of titanium dioxide particles in the cross-section was observed. The proportion of agglomerated large particles (particle size > 1 μm) was calculated, which is the agglomeration rate. Simultaneously, the average color difference ΔE of multiple different regions on the surface of the masterbatch was measured using a CR-400 colorimeter. The test results are summarized in Table 1 below: Table 1. Dispersibility test results of different samples in masterbatch

[0073] As shown in Table 1 above, the titanium dioxide masterbatches prepared using the titanium dioxide of the present invention in Examples 1 to 3, compared with Comparative Examples 1 to 5, exhibit significantly suppressed agglomeration of titanium dioxide and significantly smaller average color differences in multiple different regions. This demonstrates that the titanium dioxide for spherical particle masterbatches and its preparation method provided by the present invention can effectively solve the problem of uneven distribution of titanium dioxide and the resulting uneven coloring.

[0074] (2) Coating layer adhesion test Similar to the above experiments, different titanium dioxide samples were prepared into masterbatches, which were then repeatedly mixed three times in a twin-screw extruder at a controlled temperature of 180-200℃ and a rotation speed of 300 r / min to simulate high-temperature shearing conditions. The masterbatches were then removed and soaked in toluene for 24 hours to separate the titanium dioxide particles. The silicon content of the surface coating layer of the separated titanium dioxide was detected. Based on the silicon content, the coating layer retention rate of different samples was calculated according to the formula: coating layer retention rate = silicon content after mixing / initial silicon content × 100%. The thickness change of different titanium dioxide samples before and after mixing was also calculated through observation. The above test results are summarized in Table 2 below: Table 2. Test results of coating layer adhesion for different samples

[0075] As shown in Table 2 above, compared with Comparative Examples 1 to 5, the titanium dioxide from Examples 1 to 3, when used in masterbatches, exhibits significantly higher coating layer retention and less reduction in coating layer thickness after undergoing similar conditions such as high-temperature shearing. This demonstrates that the spherical particle masterbatch-specific titanium dioxide and its preparation method proposed in this invention, when used in masterbatches, result in a more stable coating layer adhesion on the titanium dioxide surface and maintain better stability under high-temperature conditions.

[0076] (3) Weather resistance test Similar to the above experiments, different titanium dioxide samples were prepared into masterbatches and placed in a QUV / se ultraviolet aging test chamber. Ultraviolet aging treatment was performed using a UVB lamp with a wavelength of 313 nm, controlling the irradiation intensity to be 0.8 W / m². 2 The temperature was 60℃, the relative humidity was 50%, and the aging treatment was carried out continuously for 1000 hours. Before and after the aging treatment, the color difference ΔE on the surface of the masterbatch was measured using a CR-400 colorimeter. Simultaneously, according to GB / T 2409-1980 "Test Method for Yellow Index of Plastics", the change in the yellowing index YI was detected using a YI-100 yellowing index meter. The above test results are summarized in Table 3 below: Table 3 Weather resistance test results of different samples

[0077] As shown in Table 3 above, compared with Comparative Examples 1 to 5, the masterbatches made from titanium dioxide in Examples 1 to 3 exhibit less surface color difference and a significantly lower yellowing index after ultraviolet aging treatment. This indicates that the titanium dioxide for spherical particle masterbatches and its preparation method proposed in this invention have more significant weather resistance, and when used as a raw material to make masterbatches, they can maintain color and color stability under long-term ultraviolet conditions.

[0078] (4) Mechanical property test Similar to the above experiments, different titanium dioxide samples were prepared into masterbatches. According to GB / T1040-2006 "Determination of Tensile Properties of Plastics", the different masterbatches were mixed with polypropylene resin at a mass ratio of 5:95, and injection molded into standard specimens. Tensile strength was tested using a CMT6104 universal testing machine at a tensile rate of 5 mm / min (n=5, average value). Impact toughness at 23℃ was tested using an XJUD-5.5 cantilever beam impact testing machine (n=5, average value). The test results are summarized in Table 4 below: Table 4. Test results of mechanical properties of different samples

[0079] As shown in Table 4 above, the standard specimens made from the different titanium dioxides in Examples 1 to 3 exhibit significantly higher tensile strength and impact toughness than the standard specimens made from Comparative Examples 1 to 5. This demonstrates that the spherical particle masterbatch-specific titanium dioxide and its preparation method proposed in this invention, when used as raw materials for masterbatches, can impart superior mechanical properties to the masterbatches and other products obtained through subsequent processing.

[0080] In summary, this invention solves the problems of poor dispersibility with the spherical matrix of existing silicon-coated titanium dioxide and insufficient bonding force between the coating layer and the matrix by means of composite crystalline matrix materials, multifunctional group modified coating, rare earth coupling agents, plasma activation, gradient curing, and other improvements. As a result, the silicon-coated titanium dioxide product has significantly better performance than existing coated titanium dioxide in terms of dispersibility, coating bonding force, weather resistance, and mechanical properties.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A titanium dioxide specifically for spherical particle masterbatch, characterized in that, By mass fraction, the raw materials include: 82-88% composite titanium dioxide base, 6-9% multifunctional modified organosilicon coating material, 2-4% spherical adaptable coupling agent, 0.8-1.2% dispersant accelerator, 0.1-0.3% hindered amine light stabilizer, and the balance being pH adjuster and deionized water; The raw materials for preparing the multifunctional modified organosilicon coating material include amino-modified polydimethylsiloxane, epoxytrimethoxysilane, and fluorinated organosilicon monomers in a mass ratio of 4-6:1-3:

1.

2. The titanium dioxide for spherical particle masterbatch according to claim 1, characterized in that, A method for preparing multifunctional modified organosilicon coating materials includes the following steps: A1. Take amino-modified polydimethylsiloxane, heat it, and dry it; separately take epoxy-trimethoxysilane and fluorinated organosilicon monomer, and dehydrate them respectively. A2 First, take amino-modified polydimethylsiloxane, mix it with anhydrous ethanol, stir and heat it, and react it at 35-40℃ for 10-20 min; then add epoxytrimethoxysilane dropwise at 0.3-0.5 mL / min, and continue to stir and react for 20-40 min; then cool it down to 25-30℃, add fluorinated organosilicon monomer, and stir and react at a constant temperature for 45-60 min; A3. The material system after step A2 is subjected to vacuum degassing to obtain a multifunctional modified organosilicon coating material, which is then sealed and stored away from light.

3. The titanium dioxide for spherical particle masterbatch according to claim 1, characterized in that, The composite titanium dioxide matrix includes anatase titanium dioxide and rutile titanium dioxide in a mass ratio of 8-9:

1.

4. The titanium dioxide for spherical particle masterbatch according to claim 1, characterized in that, The raw materials for preparing the spherical adaptable coupling agent include γ-methacryloyloxypropyltrimethoxysilane and rare earth modified titanate coupling agent in a mass ratio of 1-2:

1. The rare earth modified titanate coupling agent is isopropyltris(dioctylpyrophosphate) titanate modified by lanthanide elements.

5. The titanium dioxide for spherical particle masterbatch according to claim 4, characterized in that, The preparation method of spherical adaptable coupling agents includes the following steps: B1. Isopropyl tris(dioctylpyrophosphoryloxy) titanate, lanthanide compounds, and anhydrous ethanol were prepared in a mass ratio of 10:1 to 1.5:

5. The lanthanide compounds and anhydrous ethanol were mixed and heated at 45-50℃ for 20-40 min. Then, isopropyl tris(dioctylpyrophosphoryloxy) titanate was added dropwise at 0.1-0.3 mL / min. After the addition was completed, the temperature was raised to 60-65℃ and stirred for 1-3 h. The mixture was then distilled under reduced pressure to obtain the rare earth modified titanate coupling agent. B2 Take the rare earth modified titanate coupling agent obtained in step B1, cool it to below 30°C, add γ-methacryloyloxypropyltrimethoxysilane, and stir at a constant temperature under nitrogen protection until the mixture is homogeneous to obtain a spherical suitable coupling agent.

6. The titanium dioxide for spherical particle masterbatch according to claim 1, characterized in that, The raw materials for preparing the dispersion accelerator include equal masses of hyperbranched polyester dispersant and thermosensitive poly(N-isopropylacrylamide).

7. The titanium dioxide for spherical particle masterbatch according to claim 6, characterized in that, The preparation method of the dispersion accelerator includes the following steps: C1 Take hyperbranched polyester dispersant, heat it, and dry it; separately take thermosensitive poly(N-isopropylacrylamide), and purify and dry it in sequence. C2 Take the hyperbranched polyester dispersant treated in step C1, add it to anhydrous methanol, and stir; then add thermosensitive poly(N-isopropylacrylamide) and continue stirring until completely dissolved; C3 Add an antioxidant to the material system obtained in step C2, stir until homogeneous, and then distill under reduced pressure to obtain a dispersion promoter.

8. A method for preparing titanium dioxide specifically for spherical particle masterbatch as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1 Base Material Pretreatment: Take the composite titanium dioxide base material, add it to deionized water, adjust the pH value, then perform low-temperature plasma treatment, and then perform ultrasonic dispersion treatment to obtain a pretreated titanium dioxide suspension. S2 Constructing the pre-coating layer: Take the pretreated titanium dioxide suspension, add a spherical suitable coupling agent, heat and stir, and obtain a titanium dioxide particle suspension through microwave-assisted reaction; S3 Deposition of the main coating layer: Take a multifunctional modified organosilicon coating material, add it to deionized water, then add a hindered amine light stabilizer, mix well, and obtain a coating solution. The coating solution was added dropwise to the titanium dioxide particle suspension at a rate of 0.5-1 mL / min, and the mixture was stirred at a constant temperature of 60-70℃ during the process to deposit the main coating layer. Subsequently, the mixture was cured at 70-80℃ and 80-90℃ for 20-40 min and 50-70 min, respectively, to obtain the coated titanium dioxide suspension. S4 Surface Grafting Treatment: Take a coated titanium dioxide suspension, add a dispersion accelerator, mix, heat to 75-80℃, keep warm and stir to react, and obtain a preliminary titanium dioxide suspension; S5 Post-Processing: The initial titanium dioxide suspension was cooled to room temperature, then pressure filtered, washed, vacuum dried, and then subjected to air jet milling, graded and sieved. Finally, the surface was sprayed with a silane coupling agent dilution to obtain titanium dioxide for spherical particle masterbatch.

9. The method for preparing titanium dioxide specifically for spherical particle masterbatch according to claim 8, characterized in that, In step S2, the temperature is raised to 50-60℃, and the mixture is stirred at a constant temperature of 300-400r / min. The microwave-assisted power is 200-250W, and the reaction is carried out for 30-40min. In step S4, the temperature is raised to 75-80℃ and stirred at 700-800r / min for 40-60min.

10. The method for preparing titanium dioxide specifically for spherical particle masterbatch according to claim 8, characterized in that, In step S5, the particle size D50 of the granules after grading and screening is 0.22-0.28 μm, and the particle size distribution range is ≤0.08 μm.

Images